Kaliochalcite

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Kaliochalcite
General and classification
other names

IMA 2013-037

chemical formula
  • KCu 2 (SO 4 ) 2 [(OH) (H 2 O)]
  • KCu 2 (SO 4 ) 2 (OH) H 2 O (in analogy to natrochalcite)
Mineral class
(and possibly department) 		Sulphates (selenates, tellurates, chromates, molybdates and tungstates)
System no. to Strunz
and to Dana 		7.DF.15 ( 8th edition : VI / D.18)
08/31/01/02
Similar minerals Natrochalcite
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Space group C 2 / m (No. 12)Template: room group / 12
Lattice parameters a  = 8.935  Å ; b  = 6.252 Å; c  = 7.602 Å
β  = 117.318 °
Formula units Z  = 2
Frequent crystal faces {111}, {100}, {001}, {110}, {221}
Physical Properties
Mohs hardness 4th
Density (g / cm 3 ) 3.49 (calculated)
Cleavage no
Break ; Tenacity uneven; brittle
colour light green, bright grass green or almost colorless
Line color pale green to white
transparency transparent (crystals), translucent (aggregates)
shine Glass gloss
Crystal optics
Refractive indices n α  = 1.630
n β  = 1.650
n γ  = 1.714
Birefringence δ = 0.084
Optical character biaxial positive
Axis angle 2V = 55 ° (measured)
Pleochroism only occasionally very weak pleochroism
Other properties
Chemical behavior hydrolysis at room temperature followed by slow dissolution in water

Kaliochalcite is a very rarely occurring mineral from the mineral class of " sulfates (and relatives, see classification)". It crystallizes in the monoclinic crystal system with the chemical composition KCu 2 (SO 4 ) 2 [(OH) (H 2 O)] and is therefore chemically seen a hydrous potassium - copper - sulfate with an additional hydroxide .

Kaliochalcite develops pseudorhombohedral crystals up to 0.1 mm in size as well as granular to porcelain-like crusty aggregates up to 0.5 cm thick at its type locality according to [001] or flattened according to [100] . In addition, he forms pseudomorphoses after Euchlorin , Piypit or Fedotovit . The type locality of the mineral is the fumarole "Yadovitaya" the Second cinder cone on the north breakthrough of the Great fissure eruption (Great Fissure), volcano Tolbachik , Kamchatka , Far Eastern Federal District , Russia ( Russian Второй шлаковный конус Северного прорыва, Толбачик, Камчатка ).

Etymology and history

Type locality of Kaliochalcite: Ostry Tolbatschik (in the background left) and Plosky Tolbatschik (in the background right) from the south on September 11, 2014

In the last decade of the last century, Mikhail N. Murashko and Michael E. Zelenski recovered several specimens containing the mineral kaliochalcite in fumaroles on the Tolbachik volcano. However, due to the very similar X-ray diffraction pattern, this component was incorrectly determined as natrochalcite. It later at microprobe analyzes the presence of potassium-dominant analogue of Natrochalcit out, but further investigations were made strong by the fine-grained nature and polymineralic character of the aggregates that in all cases significantly (20-50 vol .-%) by Euchlorin , Fedotovit , Piypit , Langbeinite , aphthitalite and other unidentified phases were contaminated. Often microscopic inclusions of these phases caused additional reflections in the X-ray diffractograms and additional bands in the infrared spectra; they also prevented the correct determination of the water content. It was only in July 2012 that Igor V. Pekov and Dmitriy I. Belakovskiy found a step in a fumarole that contained mono-mineral aggregates and crystals of the new mineral suitable for structural analysis.

After further intensive investigations and extensive analyzes by a Russian team of scientists led by Igor V. Pekov , Oleg I. Siidra , Nikita V. Chukanov , Vasiliy O. Yapaskurt , Dmitriy I. Belakovskiy , Mikhail N. Murashko and Evgeny G. Sidorov , the species became International Mineralogical Association (IMA), which recognized it as a new mineral in 2013. It was first described as Kaliochalcite in 2014 by Igor Pekov and colleagues in the international science magazine "European Journal of Mineralogy". The authors named the mineral after its structural and crystal-chemical relationship with natrochalcite as well as its potassium content as potassium chalkite.

The type material for Kaliochalcite (holotype) is kept under catalog number 94121 in the systematic collection of the Mineralogical Museum " Alexander Evgenjewitsch Fersman " of the Russian Academy of Sciences in Moscow .

classification

The current classification of the International Mineralogical Association (IMA) counts the potassium chalcite to the tsumcorite group with the general formula Me (1) Me (2) 2 (XO 4 ) 2 (OH, H 2 O) 2 , in which Me (1), Me (2) and X different positions in the structure of the minerals of the tsumcorite group with Me (1) = Pb 2+ , Ca 2+ , Na + , K + and Bi 3+ ; Me (2) = Fe 3+ , Mn 3+ , Cu 2+ , Zn 2+ , Co 2+ , Ni 2+ , Mg 2+ and Al 3+ and X = As 5+ , P 5+ , V 5+ and represent S 6+ . To Tsumcoritgruppe include not only Kaliochalcit still Cabalzarit , Cobaltlotharmeyerit , Cobalttsumcorit , Ferrilotharmeyerit , Gartrellit , Helmutwinklerit , Krettnichit , Lotharmeyerit , Lukrahnit , Manganlotharmeyerit , Mawbyit , Mounanait , Natrochalcit , Nickellotharmeyerit , Nickelschneebergit , Nickeltsumcorit , Phosphogartrellit , Rappoldit , Schneebergit , Thometzekit , Tsumcorit , Yancowinnait and Zinc Gartrellite .

The 8th edition of the mineral classification according to Strunz , which is out of date, but still in use in some cases, does not yet list the potassium chalkite. It would belong to the mineral class of "sulphates (including selenates , tellurates , chromates , molybdates and wolframates )" and there to the division of "anhydrous sulphates, with foreign anions ", where together with kainite , natrochalcite, uklonscovite and vonbezingite it forms the kainite natrochalcite -Group with the system no. VI / D.18 would have formed.

The 9th edition of Strunz's mineral systematics, which has been valid since 2001 and is used by the IMA, does not yet know about potassium chalkite. Here it would also be classified under the category of "Sulphates (selenates etc.) with additional anions, with H 2 O". However, this is further subdivided according to the relative size of the cations involved , so that the mineral would be found in the sub-section “With large and medium-sized cations” according to its composition , where, together with natrochalcite, the unnamed group with the system no. 7.DF.15 would form.

Also the systematics of minerals according to Dana , which is mainly used in the English-speaking world , would classify the potassium chalkite in the class of "sulfates, chromates and molybdates" and there in the category of "water-containing sulfates with hydroxyl or halogen". Here it could be found together with natrochalcite in the unnamed group 08/31/01 within the subdivision of " Hydrogen sulfates with hydroxyl or halogen with (A + B 2+ ) (XO 4 ) Zq × x (H 2 O) ".

Chemism

Five microprobe analyzes on the holotype of the potassium chalkite resulted in mean values ​​of 40.28% CuO; 40.97% SO 3 ; 11.01% K 2 O; 0.04% Na 2 O; 0.39% ZnO; 0.15% FeO; 0.27% CaO and 5.84% H 2 O. On the basis of ten oxygen atoms (and an OH: H 2 O ratio calculated from the charge balance ), the empirical formula (K 0.94 Ca 0, 02 Na 0.01 ) Σ = 0.97 (Cu 2.03 Zn 0.02 Fe 0.01 ) Σ = 2.06 S 2.05 O 8.20 (OH) 1.01 (H 2 O) 0 , 79 , which was idealized to KCu 2 (SO 4 ) 2 [(OH) (H 2 O)]. This ideal formula requires levels of 11.97% K 2 O; 40.45% CuO, 40.71% SO 3 and 6.87% H 2 O.

Potassium chalcite is the potassium-dominant analogue of sodium- dominated natrochalcite. As early as 1989, through microprobe analyzes on natrochalcite crystals from the “Mina Santiagina”, Sierra Gorda, Región de Antofagasta , Chile , a substitution of sodium by potassium in the range of ≈ 2% up to 7% was found. Since the intermediate potassium-sodium-sulfate (K 0.5 Na 0.5 ) Cu 2 (SO 4 ) 2 [(OH) (H 2 O)] is known as a synthetic compound, there is at least theoretically the possibility of a complete one Mixed crystal series between natrochalcite and potassium chalcite.

For the numerous synthetic equivalents of potassium chalcite, see natrochalcite.

Crystal structure

Crystal structure of potassium chalcite

Potassium chalcite crystallizes in the monoclinic crystal system in the space group C 2 / m (space group no. 12) with the lattice parameters a  = 8.935  Å ; b  = 6.252 Å; c  = 7.602 Å and β = 117.318 ° as well as two formula units per unit cell . Template: room group / 12

The crystal structure of the Kaliochalcits is by chains by Jahn-Teller effects disturbed Cu 2+ O 6 - octahedrons formed by common edges. These chains are of SO 4 - tetrahedra and hydrogen bonds and form in this way, {Cu 2 (SO 4 ) 2 [(OH) (H 2 O)]} - layers. The connection between these layers is made by K + ions and hydrogen bonds. Oxygen atoms belonging to the H 2 O molecules and the OH groups occupy the O (3) positions statistically.

Kaliochalcite is isotypic (isostructural) to the monoclinic representatives of the tsumcorite group such as tsumcorite and lotharmeyerite and to the synthetic equivalents mentioned above.

properties

Costume and habitus of Kaliochalcite crystals (the same colors represent the same surface shapes)
Kaliochalcite crystal drawing 1.png
Kaliochalcite crystal with little area
Kaliochalcite crystal drawing 2.png
extensive Kaliochalcite crystal


morphology

Kaliochalcite develops pseudorhombohedral crystals at the type locality, sometimes elongated according to [001] or flat, sometimes bent according to [100], which reach maximum sizes of 0.03 × 0.1 mm. Forms that determine costume are the prism {111} and the pinacoid {100}. The basic pinacoid {001} and in some cases also the prisms {110} and {221} occur subordinately. Typical crystals show the habit of an elongated pseudo- rhombohedron , the costume of which is formed by the flat shapes {111} and {100} as well as the small triangular shapes of the terminating base pinacoids {001} (cf. the crystal drawings on the right).

In addition, potash calcite forms massive, porcelain-like or porous, polymineral crust-like aggregates that can cover several dozen square centimeters in the upper parts of the fumaroles and are up to 0.5 cm thick. Fine-grain potassium chalcite with individual crystals, which typically reach a size of 5 µm or less, form the main component of these crusts. In most cases, the crust-shaped aggregates represent partial pseudomorphoses after primary anhydrous K-Cu sulfates such as Euchlorin, Fedotovite, Piypit, Kamchatkit , Alumoklyuchevskit or Wulffit .

physical and chemical properties

The crystals of Kaliochalchite are light green, bright grass green or almost colorless, their line color is pale green to white. The surfaces of the translucent (aggregates) to transparent crystals have a glass-like sheen , which agrees well with the values ​​for light refraction . Fine-grain, porcelain-like aggregates, on the other hand, are matt.

Potash calcite has a medium refraction (n α  = 1.630, n β  = 1.650, n γ  = 1.714) and a very high birefringence (δ = 0.084). Under the microscope the mineral is colorless or pale green with only very weak pleochroism in transmitted light .

In contrast to most of the other representatives of the tsumcorite group, no cleavage could be observed in the crystals of the potassium chalcite . Due to its brittleness , however , it breaks like amblygonite , with the fracture surfaces being uneven. The mineral has a Mohs hardness of 4 and is therefore one of the medium-hard minerals that, like the reference mineral fluorite, can be easily scratched with a knife. Due to the porosity of the potassium chalchite, its density cannot be determined experimentally; the calculated density is 3.49 g / cm³.

The mineral hydrolyzes at room temperature and then slowly dissolves in water.

Education and Locations

As an extremely rare mineral formation, Kaliochalcite could only be described from one site so far (status 2018). As type locality , the two are fumaroles "Yadovitaya" and "Arsenatnaya" ( "The Toxic") in the apical part of the Second ash cone on the north breakthrough of the Great fissure eruption (Great Fissure), volcano Tolbachik ( coordinates of the volcano Tolbachik ), Kamchatka , Federal District Further East , Russia . The mineral was also found in the "Glavnaya Tenoritovaya" ("Great Tenorite"), the "Zelenaya" ("Green") and two unnamed fumaroles, all also at the northern breakthrough of the Great Fissure Eruption of the Tolbachik volcano.

Potash calcite is a typical secondary mineral which is formed in volcanic fumaroles when sublimated high-temperature K-Cu sulfates react with atmospheric water vapor at temperatures <100–150 ° C. Here it is one of the most common copper minerals within the mainly sulphate-based incrustations that have formed in the upper, moderately hot parts of the mineralized zones in the fumaroles.

In the “Yadovitaya” fumarole, the most important high-temperature sublimate minerals are Euchlorin, Fedotovite, Piypit, Chalcocyanite , Alumoklyuchevskit, Langbeinite, Steklite , Hematite , Tenorite , Tolbachite ; aphthitalite, kamchatkite, anhydrite , lyonsite , pseudolyonsite , lammerite , lammerite-β , orthoclase (As-containing variety), rutile (Fe- and Sb-containing varieties), pseudobrookite , vergasovaite , cupromolybdite etc. are subordinate . In contrast, the fumarole water-containing minerals have been encountered in the relatively low-temperature outer zone: Kaliochalcit, Cyanochroit , Chlorothionit , gypsum , Belloit , Avdoninit , Eriochalcit , Kröhnkit etc., all of which to the actual Paragenesis minerals are to be counted. In the "Arsenatnaya" -Fumarole are Tenorite, hematite, Euchlorin, Wulffit, Aphthitalith, langbeinite, sylvite , halite , anhydrite, Chalcocyanit, Dolerophanit , Krasheninnikovit , Lammerit, Johillerit , Bradaczekit , Urusovit , Ericlaxmanit , As-containing orthoclase and Fluorophlogopite key primary sublimate minerals, while the secondary minerals are mainly formed by gypsum, potassium chalcite, opal and various, unidentified aluminum sulfates.

use

Due to its extreme rarity, potash calcite is only of interest to mineral collectors.

See also

literature

  • Igor V. Pekov, Oleg I. Siidra, Nikita V. Chukanov, Vasiliy O. Yapaskurt, Dmitriy I. Belakovskiy, Mikhail N. Murashko, Evgeny G. Sidorov: Kaliochalcite, KCu 2 (SO 4 ) 2 [(OH) (H 2 O)], a new tsumcorite group mineral from the Tolbachik volcano, Kamchatka, Russia . In: European Journal of Mineralogy . tape 26 , no. 4 , 2014, p. 597-604 , doi : 10.1127 / 0935-1221 / 2014 / 0026-2394 ( researchgate.net [PDF; 406 kB ; accessed on January 24, 2018]).
  • Kaliochalcite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 362 kB ; accessed on February 12, 2018]).

Web links

Individual evidence

  1. ↑ a b c d e f g h i j k l m n o p q r s t u v Igor V. Pekov, Oleg I. Siidra, Nikita V. Chukanov, Vasiliy O. Yapaskurt, Dmitriy I. Belakovskiy, Mikhail N Murashko, Evgeny G. Sidorov: Kaliochalcite, KCu 2 (SO 4 ) 2 [(OH) (H 2 O)], a new tsumcorite-group mineral from the Tolbachik volcano, Kamchatka, Russia . In: European Journal of Mineralogy . tape 26 , no. 4 , 2014, p. 597-604 , doi : 10.1127 / 0935-1221 / 2014 / 0026-2394 ( researchgate.net [PDF; 406 kB ; accessed on January 24, 2018]).
  2. ↑ a b c Kaliochalcite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 362  kB ; accessed on February 12, 2018]).
  3. ^ Igor V. Pekov: Minerals first discovered on the territory of the former Soviet Union . 1st edition. Ocean Pictures, Moscow 1998, ISBN 5-900395-16-2 , pp. 1-369 .
  4. ↑ Werner Krause, Klaus Belendorff, Heinz-Jürgen Bernhardt, Catherine McCammon, Herta Effenberger, Werner Mikenda: Crystal chemistry of the tsumcorite-group minerals. New data on ferrilotharmeyerite, tsumcorite, thometzekite, mounanaite, helmutwinklerite, and a redefinition of gartrellite . In: European Journal of Mineralogy . tape 10 , 1998, pp. 179-206 , doi : 10.1127 / ejm / 10/2/0179 .
  5. ↑ a b Gerald Giester: The crystal structures of Ag + Cu 2 (OH) (SO 4 ) 2 • H 2 O and Me + Cu 2 (OH) (SeO 4 ) 2 • H 2 O [Me +  = Ag, Tl , NH 4 ], four new representatives of the natrochalcite type, with a note on natural natrochalcite . In: Journal of Crystallography . tape 187 , no. 3-4 , 1989, pp. 239-247 , doi : 10.1524 / zkri.1989.187.3-4.239 .
  6. ↑ Anton Beran, Gerald Giester, Eugen Libowitzky: The hydrogen bond system in natrochalcite-type compounds - to FTIR spectroscopic study of the H 3 O - unit . In: Mineralogy and Petrology . tape 61 , no. 1-4 , 1997, pp. 223-235 , doi : 10.1007 / BF01172486 .
  7. ↑ Gerald Giester, Josef Zemann : The crystal structure of the natrochalcite-type compounds Me + Cu 2 (OH) (zO 4 ) 2 • H 2 O [Me +  = Na, K, Rb; z = S, Se], with a special reference to the hydrogen bonds . In: Journal of Crystallography . tape 179 , no. 1-4 , 1989, pp. 431–442 , doi : 10.1524 / zkri.1987.179.14.431 ( rruff.info [PDF; 484 kB ; accessed on January 24, 2018]).
  8. ↑ Mindat - Kaliochalcite
  9. ↑ Mindat - Number of localities for Kaliochalcite
  10. ↑ Find location list for Kaliochalcit at the Mineralienatlas and at Mindat